COVER - shares	9 Months Ended
	Sep. 30, 2022	Nov. 01, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	001-33961
Entity Registrant Name	HILL INTERNATIONAL, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-0953973
Entity Address, Address Line One	One Commerce Square
Entity Address, Address Line Two	2005 Market Street, 17th Floor
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19103
City Area Code	215
Local Phone Number	309-7700
Title of 12(b) Security	Common Stock, par value $0.0001
Trading Symbol	HIL
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,086,992
Entity Central Index Key	0001287808
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3